December 2013

Auld Lang Syne

As we come to the end of another year in Amigaland it's a time to reflect on the past 12 months and look forward to what the new year will bring.

Χρόνια Πολλά & Καλή Χρονιά :-)

  • By: 32bitos
  • Posted on: 30 December 2013



τους αρέσει ο

ύπνος, αλλά ξυπνούν

πάντα με καλή διάθεση,

όσους χαιρετούν ακόμα με ένα φιλί,

όσους δουλεύουν πολύ, αλλά δεν ξεχνούν

RTC Progress

RTC appears to be working and keeping the date and time across cold-starts.

I picked the Epson RTC-72423 which is about a $6 chip, but is obviously directly compatible with the OKI Semiconductor MSM6242B.  The design, including the battery supervisor, had never been tested — not even as a prototype… and appears to have worked the first time!

I needed to do a “setclock reset”, set the date via “Date 28-Dec-13 02:26:00″ command, and then did a “setclock save”  Subsequent setclock loads brings it back!

Found potential race condition on writes

After looking at datasheets for the 273 latches used and 74act74 flipflop used, the worst case propagation delay is something like 12.3ns.

But my NAND gate ACT00 logic which is triggered by the same CAS signals has a lower propagation delay of between 1-9ns.

So despite a 0ns setup time, it’s possible that I’m violating the SRAM setup times during a write by dropping /CE before the addresses have stabilized into the memory.

I haven’t come up with a solution yet, but it will likely involve adding an additional gate or two to increase the propagation delay.


Populated PCB with fix for unneeded inverter


Lots of progress but little time to talk about it.

Here’s the fully populated card installed.  There were two issues identified so far with the PCB design.  One, the battery holder silkscreen was upside down.  The second fix involved an inverter that needed removed whenever we decided to migrates from a flip-flop(74LS74) design to a SR NAND latch made out of NAND(74LS00) gates.

The memory tests are passing at 100% now!@#

However, there is still a minor issue with how the card responds on bootup, and I’m investigating!

PCBs have arrived!

Just in time for Christmas, the PCBs have arrived from China.  I used Seeed Studio (Fusion PCB Service) and they look pretty good.  Here’s the first look at them.

I’m just about to solder one up, so wish me luck!


Christmas Cheer

I'm now back home to Summer in New Zealand, complete with a Northern hemisphere cold (sniff!), following my flying visit to Pianeta Amiga, which was held in a rather chilly Bologna in Northern Italy. Nevertheless the Pianeta Amiga show was a fun affair, even though the attendance was quite small compared to previous years. That didn't stop everyone who did attend from having a good time. I will write more about my Pianeta trip in my next blog but, for now I would like to wish all Amiga enthusiasts, whatever your Amiga colour, hue or flavour a very Merry Christmas.

Assist 1.72

Assist 1.72 is now available to download from OS4Depot. This update fixes a few minor bugs in Preferences. There are also 5 new articles to enjoy.
New users can grab the latest version from OS4Depot, while existing users can update to this latest release via AmiUpdate.

Assist 1.71

Assist 1.71 is now available to download from OS4Depot. This minor update fixes an issue that could occur when the user specified destinations for downloads and/or the log file. Apart from this fix there are also 10 new articles and some others that have been updated.